Innovative sensing technologies applied to post-consumer polyolefins recovery

Polyolefins can be considered as one of the most important polymers for consumer goods being polyethylene (PE) and polyropylene (PP) the most commonly utilized. Even if post-consumer wastes could be considered as a good resource of polyolefins, their recovery and recycling is very low. The reason can be mainly attributed to the complexity of these wastes according to different polymers (rubber, foam, etc) and polluting (not polymers) materials (wood, aluminium, copper, stones, glass, etc) commonly present in plastic waste streams. In this paper two innovative sensing technologies, and related detection architectures, in order to develop new sorting strategies for pure PP and PE recovery from mixed waste, are presented and discussed. The first one based is on an hyperspectral imaging (HSI) approach and the second one is based on differential melting point (DMP) approach. HSI was investigated to evaluate the possibilities of this technology to determine the quality of waste plastic feed (in terms of presence and characteristics of polyolefin and contaminants). The DMP technology was developed to utilize the different PE and PP particles melting characteristics to perform their quality control as resulting from magnetic density separation (MDS), Results showed as both the approaches can be profitably utilized to develop reliable detection and/or processing architectures and related quality control strategies to implement inside the different sections of a plastic waste recycling plant.